One knows laser guidance systems for missiles of the “beamrider” type, in which a laser signal receiver located in the rear part of the missile detects the laser signal, analyzes it and determines the position of the missile. The latter centers itself automatically relative to the beam. Two alternated patterns ensure coding of the horizontal and vertical position of the missile.
This guidance system is deemed to be very precise in static mode. However, when the missile is launched, for example from an armored vehicle turret under actual operating conditions, i.e. when the vehicle or the target is moving, and particularly on uneven land or when there is wind, the precision of the guidance is deteriorated.
Furthermore, it is known that currently, an armored vehicle turret typically comprises a sight system, which provides the gunner and the commander with a day channel and a night (or thermal) channel, as well as a laser telemeter. The gunner and the commander have both at their disposal a station with a joystick, which makes it possible to give the azimuth and elevation (or height or altitude) command to the sight system, and therefore to modify the line of sight, as well as a control screen. The commander's sight system also provides a panoramic view. The image in the sight system is gyrostabilized relative to the ground owing to an integrated gyroscopic system. This means that the line of sight remains parallel to itself irrespective of the movements of the vehicle. The line of sight and the line of fire are parallel to each other owing to the power control system which commands the turret in azimuth and the cannon in elevation, according to the values communicated by the sight system.
The guidance system, comprising a laser line and a control camera that are perfectly harmonized, i.e. aligned or optically matched, is fastened to the launcher or to the vehicle, and may or may not be integrated into the sight system of the vehicle, or on a station separated from the vehicle. According to the state of the art, the means for modifying the direction of the laser guidance line are rudimentary and do not allow precise, fluid and regular control to engage a moving target. Currently, any modification in the guidance line is done manually, without assistance from the optic, either by moving the turret, or by moving the guidance system of the missile. This causes somewhat mediocre performance and also does not offer many firing opportunities.
Document DE 42 03 474 A discloses a sight device for a gunner of an armored vehicle, in which the gunner observes the target by means of a day/night periscope installed in the turret, the optical axis of which is harmonized with the axis of an integrated laser telemeter, operating according to the pulse return principle. In order to optimize the firing range and precision, there is provision for having, in the functional field of the laser telemeter, a guidance laser transmitter as a separate entity, in the guidance beam of which flies a projectile provided with a receiver in its rear part and the optical axis of which is generated so as to be harmonized with the optical axis of the day/night periscope. The guidance laser transmitter is positioned in the turret of the tank in the region between the day/night periscope and the reactive modules of the armored vehicle located behind the sight station. A device of this type was on the Leopard II tank.
In document DE 41 37 843 A1, the weapon system includes a sight module equipped with an integrated laser telemeter. A laser beam is modulated outside the sight module and coupled to the optical path of the laser telemeter via a fold mirror, to serve as a guidance beam for a remotely guided projectile.
The inventoried missile firing stability and precision limits, in the case of the solutions of the state of the art, are related, depending on the case, to:                the movement inside the vehicle (occupants, motor, wind, etc.);        scenarios involving firing at a moving target;        the moving vehicle; in this case, the use of the optical system may be contemplated, but is not really recommended because many conditions would have to be met (flat terrain, etc.).        